Community Forums

sevd · 11-12-2021, 11:29 AM

I am looking for any insight on what's going on with my recently purchased (September) 2017 Monaco Diplomat 43S.

Driving from Kansas City, MO, I broke down in October near Kanab, UT with a mysterious coolant leak and running hotter than normal. Long story short, the coolant was being pressurized and was leaking under heat and load only. Eventually, while testing it in the shop, it became obvious there was likely a cracked head or blown head gasket.(Of course there are a variety of other things that could pressurize the coolant.)

The current estimate for repair does not address whatever caused the failure at only 13,200 miles. I have zero confidence that the proposed replacing of the head gasket and ruined emissions equipment will last and will probably only last a few thousand miles. (The estimate is for $12,800.)

Here's why: I've learned that in August 2019 at 9,700 miles, the engine suffered hydrolock from a faulty fuel injector that was dumping excessive fuel into one of the cylinders. The Cummins-certified shop repaired the engine under warranty which included replacing the fuel injector, two pistons and sleeves, some turbocharger parts, and a new (remanufactured) head. Just over 3,000 miles later, it blows.

My current thinking is that that engine should have probably been replaced in 2019. I also think that there is either something wrong with the repaired pistons and cylinder sleeves or there is damage from the 2019 incident that was not found nor repaired. I am still within the Cummins 5 year/100k mile warranty. However, it is up at the end of January, 2022 and I'm not comfortable with just fixing the head gasket and seeing what happens.

What do y'all think?

wolfe10 · 11-12-2021, 11:40 AM

Until the head comes off, impossible to know the root cause and whether a repair will be permanent or whether replacement will be necessary.

Until the root cause is revealed, we would just be shooting from the hip.

bubby124 · 11-12-2021, 04:51 PM

I think they should replace the engine or extend warranty but Cummins will disagree you might need a lawyer more then a mechanic just my thoughts

bentjm · 11-13-2021, 10:30 AM

I would also have a discussion with wherever you purchased the coach. The previous engine work should have been disclosed.

Ray,IN · 11-13-2021, 01:09 PM

I would think a compression test would reveal the root cause, I assume was that performed. If it was, the mechanic knows which cylinder is leaking.

sevd · 11-13-2021, 05:08 PM

Quote:

Originally Posted by wolfe10

Until the head comes off, impossible to know the root cause and whether a repair will be permanent or whether replacement will be necessary.

Until the root cause is revealed, we would just be shooting from the hip.

The head is off, but the shop has not determined any root cause. I'm just looking for suggestions on what to ask them to do, such as a compression test.

sevd · 11-13-2021, 05:09 PM

Quote:

Originally Posted by bubby124

I think they should replace the engine or extend warranty but Cummins will disagree you might need a lawyer more then a mechanic just my thoughts

I am thinking the same, especially because it should probably have been replaced back in 2019.

sevd · 11-13-2021, 05:10 PM

Quote:

Originally Posted by bentjm

I would also have a discussion with wherever you purchased the coach. The previous engine work should have been disclosed.

I bought it from a private owner. I agree that it should have been disclosed but it was in working order when I bought it. Buyer beware, as we all know.

sevd · 11-13-2021, 05:14 PM

Quote:

Originally Posted by Ray,IN

I would think a compression test would reveal the root cause, I assume was that performed. If it was, the mechanic knows which cylinder is leaking.

Yes, I'm anxious for this to be done. I can't believe they had it in the shop, took off the head, and did nothing to determine the cause. It may be a communication problem, since you don't get to talk to the mechanics.

wolfe10 · 11-13-2021, 05:20 PM

Quote:

Originally Posted by sevd

The head is off, but the shop has not determined any root cause. I'm just looking for suggestions on what to ask them to do, such as a compression test.

Nope, with the head removed, no compression test!

Xmcdog · 11-13-2021, 05:29 PM

Quote:

Originally Posted by wolfe10

Nope, with the head removed, no compression test!

You beat me to it. Was about to say the same thing.
$13 k sounds a tad much for a head gasket. What else are they doing?
How long do they warranty their work? 3000 miles before breaking down again for the same reason. Thats nuts. That should be on their dime.

I'm with you on just replacing the gasket. There is something else that has happened from the hydrolock. Maybe the block was damaged somehow. In which case I would look at a crate engine or even a used one.

Consider having it towed to a indipendant shop.

Sorry to hear of your troubles. Hopefully you can get it repaired without costing too much.

Caliber · 11-13-2021, 05:56 PM

Quote:

Originally Posted by sevd

The current estimate for repair does not address whatever caused the failure at only 13,200 miles. I have zero confidence that the proposed replacing of the head gasket and ruined emissions equipment will last and will probably only last a few thousand miles. (The estimate is for $12,800.)

<snip>

I am still within the Cummins 5 year/100k mile warranty. However, it is up at the end of January, 2022 and I'm not comfortable with just fixing the head gasket and seeing what happens.

What do y'all think?

Is it now being repaired under warranty????

jacwjames · 11-14-2021, 07:25 AM

Quote:

Originally Posted by bubby124

I think they should replace the engine or extend warranty but Cummins will disagree you might need a lawyer more then a mechanic just my thoughts

I would try and get copies of all the work done in the first failure.

Get all the in info on this failure. Did the Cummins shop pull any codes off the ECM? What other diagnostics did they do before pulling the head?

I would try and get a copy of the ECM settings and how it was running prior to failure. There should be history if it started throwing fault codes, which may have been happening soon after the first repair.

Now call Cummins and talk to someone about a new engine or at minimum an extended warranty. If you don't get satisfaction move up the chain of command. At some point you may have to lawyer up, this would be a last resort but may be necessary.

randomledder · 11-14-2021, 07:57 AM

Something doesn’t add up here. Where is the coolant leaking under load? Is it an external leak? I have never seen a bad injector cause a hydro locked engine. There simply isn’t enough fuel in the rail to hydro lock an engine with fuel. A bad egr cooler on the other hand will hydro lock an engine. I have seen it many times. The replacement of two pistons and liners doesn’t make much sense either. Maybe there were failed injectors that caused a piston failure taking out the liners with them. Now that the cylinder head is off they should check the liner protrusion, there have been cases where the protrusion is low and the head gasket doesn’t seal properly. The counter bores can be machined and shims used to correct this issue.